The present invention relates to a blower beater mill whose rotor has a beater portion with beater arms. Two connected parts with the beater arm bases are fastened in the hub rings of the shaft and the fastening elements of the two beater arm portions are provided above the shaft crests of the hub rings. Such mills suck in hot flue gases to dry the moist material to be ground through a suction shaft from the firebox (or combustion chamber) of the boiler. Thus, the rotor is subject to a high temperature load during the grind-dry process or during the start and stopping of the mill.
The present invention aims to protect the rotor against temperature load. This shall not interfere with replacement of the beater arms of the blower beater mill.
There is already known a beater mill (German Laid-Open Document No. 1,216,076) where individual beater arms are interchangeably fastened to the rotor and where intermediate pieces are used which are fastened to the hub rings. Every beater arm is held between an intermediate piece pair and fastened by means of a bolt located above the hub rings. Also, a slot provided in the lower face surface of the beater arm engages a bolt located between the hub rings. Because of this swinging suspension of the beater arms, vibrations of the beater arm system manifest themselves in an unfavorable manner.
Accordingly, it is the object of the present invention to protect the mill shaft of a blower beater mill of the above type in such a way that high temperatures at the shaft crest are avoided, and the temperature difference across the shaft cross-section is reduced, and also so that the beater arms can be replaced individually.
Another object of the present invention is to provide a blower beater mill of the foregoing character in which the arrangement is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide a beater mill arrangement, as described, which may be readily maintained in service and which has a substantially long operating life.